Hydrothermal Treatment of Microalgae for Biofuel Production

Microalgae as a source of biofuel is not only important for sustainable energy but is also vital for meeting emission standards. However, the drying, extraction, and catalytic conversion processes necessary to convert microalgae to fuel are cost prohibitive compared to petroleum diesel fuel at its current price. To enable this sustainable fuel resource, the present project aims to investigate and optimize biofuel production using Hydro-Thermal Liquefaction (HTL) process. The algae will be directly combusted in a PARR Reactor, co-fueled with diesel or biodiesel to power engines. The algae components of proteins, carbohydrates, and oil have a combined heat of combustion near that of ethanol. In our preliminary research, an HTL process was developed where the algae are cooked at different experimental conditions, such as DI water content, diesel volume, algae mass, temperature and pressure, duration of cooking and de-oxygenation. HTL can be performed on wet substances without drying, so the main issue is controlling the salt content in the algae. The microstructural studies were conducted on the algae samples processed for 30 minutes and 2 hours show the presence of carbon to oxygen in 2:1 with the rest of the elements such as Cl, K, Na, P, S, and Mg in less than 1.5 wt%. Overall, this research will provide data critical to meeting the potential of microalgae as a directly combustible biofuel.